The guidance in Manual D states that you should reduce your trunk duct around the 24 foot mark or when your velocity drops by half from your initial starting point. The 24’ doesn’t need much...
Type: Posts; User: Ed Janowiak
The guidance in Manual D states that you should reduce your trunk duct around the 24 foot mark or when your velocity drops by half from your initial starting point. The 24’ doesn’t need much...
Page N31 Manual D gives gap height that will provide enough area to maintain a velocity of 300 feet per minute through the gap. The gap provides enough area to keep the pressurization so it will not...
You do need to know the sensible BTUH requirement for each room so you can calculate the CFM to each room and size the branch run ( yes to the J question).
But if you can’t access them knowing...
If you understand how to calculate your longest circulation pass generally referred to as the critical path in Manual D you don't need the physical manual to complete the task.
You can go on the...
Most of the states you have listed do not have state licenses. They have town / village or city licenses and the rules can be very different in neighboring towns. NJ has yet to find another state...
Use a TrueFlow grid from the Energy Conservatory to get the most accurate / easiest to use results for measuring airflow in a residential application.
Will the final version include duct leakage ( ASHREA 152) ?
https://www.energy.gov/sites/prod/files/2014/01/f6/152faip2003_prc3.xls
Scroll down in the link and select what year you’re calculating for, fill it out and it will calculate it for you. It’s quite simple.
https://www.redcalc.com/red-calc-free/
There is a calculator in that link. Also a bunch of good info.
Pretty simple, the unit(s) were touted as being able control humidity like no other unit could. Both houses I was in had RH> 60% with dry bulb temps in the mid to low 70’s. < 400 CFM PT.
I put a...
only if the SHR of the home is between .8 and .85.
I very rarely see the target in that range.
Oversized is easily defined, if you can’t maintain < 50%RH on a design day in a green grass climate you’re oversized. If you can’t maintain 55% RH a humid climate your oversized. A 62 or 63° web...
https://images.platforum.cloud/uploads/20190723/d2c40bab99f43c47ff02f88005996a05.jpghttps://images.platforum.cloud/uploads/20190723/b31f760d0a84d115cb2893bd0ad2f5cc.jpg
Sent from my iPhone...
Stick your hand 6 inches in front of your face and blow into it, you can feel that right?
Stick your hand 6 inches in front of your face and sucking real hard, you can’t feel that right? That is...
You can reduce or eliminate stagnant areas in a room with correct supply register selection and placement. You cannot do the same with return placement.
Manual S give us guidance on how to cover the sensible and latent BTUH gain by manipulating the airflow across the evaporator coil.
Your target SHR should come from a load calc (Manual J) Period....
Manual J doesn’t prescribe airflow, Manual S does. The sensible heat ratio of the house ( divide your sensible gain by your total gain) from your Manual J calc.
If it’s above .85 the recommended...
Airflow has a significant effect on the SHR of the system. I dont agree with the statement a larger evap will remove more latent or more sensible heat unless you look at the air flow. You can move...
Why do you keep using a TEL of 500? That's the max, it should never be used as an example, especially in a new design.
An ASP of .2 is all that's needed with a decent duct design of 300 TEL.
...
Are you really using made up friction rates then want to pick the fly crap out the pepper when it comes to the pressure drop on filters?
Come on man!
It's a variable speed ECM fan so the PSC info you just gave would not apply.
I'd be leary of anything else the person who told you about the 78 degrees has to say.
Google AHRI standard 210 240 it will show you the temps the systems are tested at. 80 inside at 50% RH 82...
I'm still lost on the ak factor for a filter.
I can find PD @ 300 FPM for filters I do designs with but ak for a filter is something I think you're making up.
http://hvac-talk.com/vbb/showthread.php?1110521-Capacity-Verification
Step by step
I don't think anything is being ignored if the guidance is to keep the velocity through the filter below 300 FPM. Filters are often misized, but that is more due to people using rules of thumb...
The Liquid line solenoid was required to get the 12 SEER (or whatever target) rating out of systems of that era. The LLS maintained a solid column of liquid to the metering device on start up.
...
30% on VS, not 35.
Maybe I'm splitting hairs.
I have a thing for people saying things are over sized when they are not.
An oversized system will not be able to maintain humidity, it will...
You said the system is oversized 99% of the time
Do you believe that or not?
I'm aware of what the 1% is in reference too.
On the topic of 2 speed, look at the SHR of the space and the SHR of the system on low speed. They are not always a good fit.
I've been very underwhelmed with the low speed performance of a lot...
I don't concur.
Ponder this.
My area as well as many, 75 dry bulb 62 wet (50% rh) is the target.
Systems can maintain this more than 1% of the time. So we are not oversized 99% of the time....
If that is the case, how do you get proper throw from a register at all speeds?
CFM = area x volicity. If the CFM is cut in half and the area hasn't changed the volicity is cut in half and the...
Very sad to see this Bennie is the right kind of people. RIP.
What is "unique enthalpy"?
You should be able to find that info through design star or design star pro. Your distributor should hook you up with that.
Actually it's nothing like water flow. The pump laws say if you double the pipe size and maintain pressure you double the flow. Laws of vacume tell us you double the hose size you increase flow by a...
If the slanted section is a combo ceiling / roof treat it as such. If it's a ceiling with an attic do it that way. Both are choices in the program.
How come no one asks about airflow?
Need to know your super heat too.
What is required?
They are yanking your chain. A simple Google search will show you the cost.
Dick is a true gentleman if you get the chance to meet and talk with him you'd understand what I mean. He has done a lot for our industry that most people will never see. He's a good egg.
Doesn't look professional IMO.
There is no such thing as 4 ton evap coil.
There is a coil and outdoor unit that produce a specific amount of cooling at specific conditions that can be looked up in the manufacturers application...
Again I ask how do you know this?
Without knowing the sensible heat ratio there is no information to calculate if greater latent removal is required.
I've also done1000's and need more info than what has been posted so far.
How do you determine your air flow without knowing the SHR?
The gain as calculated is grater than 36000 the nominal not actual capacity of a 3 ton system.
Without knowing the SHR of the gain how can you calculate what size is required to meet the gain?
...
You need a system that will 100% meet the sensible gain, 100% meet the latent gain and not exceed the total gain by 115%. This is what is called proper equipment selection.
I highly doubt 3...
The 150 CFM that's going into this room, did you measure it? Or are you guessing based on the size of the duct and some made up friction rate?
No I'm not saying that.
I'm saying in your scenario if we have a properly sized and at least a half decent supply register selection and placement we can get equal (acceptable) H&C performance....
How many CFM were coming out of the supply in the office before the return was added and how many after?
this can all be quantified :.02:
The thing is we don't have to:
"let's just say he was supply 150 CFM of air"
It can actually be quantified, there is no reason to throw made up scenarios out there. The room cooled off because...